File:  [gforth] / gforth / engine / ecvt.c
Revision 1.4: download - view: text, annotated - select for diffs
Sun Mar 28 16:10:03 1999 UTC (22 years, 6 months ago) by anton
Branches: MAIN
CVS tags: HEAD
minor bugfixes

    1: /* cheap ecvt replacement
    2: 
    3:   Copyright (C) 1998 Free Software Foundation, Inc.
    4: 
    5:   This file is part of Gforth.
    6: 
    7:   Gforth is free software; you can redistribute it and/or
    8:   modify it under the terms of the GNU General Public License
    9:   as published by the Free Software Foundation; either version 2
   10:   of the License, or (at your option) any later version.
   11: 
   12:   This program is distributed in the hope that it will be useful,
   13:   but WITHOUT ANY WARRANTY; without even the implied warranty of
   14:   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   15:   GNU General Public License for more details.
   16: 
   17:   You should have received a copy of the GNU General Public License
   18:   along with this program; if not, write to the Free Software
   19:   Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
   20: */
   21: 
   22: #include <stdio.h>
   23: #include "config.h"
   24: #include <math.h>
   25: extern double floor(double);
   26: extern double pow10(double);
   27: 
   28: #define MAXCONV 0x40
   29: char scratch[MAXCONV];
   30: 
   31: char* ecvt(double x, int len, int* exp, int* sign)
   32: {
   33:    int i, j;
   34:    double z;
   35:    
   36:    if(len > (MAXCONV-1)) len = MAXCONV-1;
   37:    
   38:    if(x<0)
   39:      {
   40: 	*sign = 1;
   41: 	x = -x;
   42:      }
   43:    else
   44:      {
   45: 	*sign = 0;
   46:      }
   47: 
   48:    if(x==0)
   49: 	*exp=-1;
   50:    else
   51:      *exp=(int)floor(log10(x));
   52:    x = x / pow10((double)*exp);
   53:    
   54:    *exp += 1;
   55:    
   56:    for(i=0; i < len; i++)
   57:      {
   58: 	z=floor(x);
   59: 	scratch[i]='0'+(char)((int)z);
   60: 	x = (x-z)*10;
   61:      }
   62:    
   63:    if((x >= 5) && i)
   64:      {
   65: 	for(j=i-1; j>=0; j--)
   66: 	  {
   67: 	     if(scratch[j]!='9')
   68: 	       {
   69: 		  scratch[j]+=1; break;
   70: 	       }
   71: 	     else
   72: 	       {
   73: 		  scratch[j]='0';
   74: 	       }
   75: 	  }
   76: 	if(j<0)
   77: 	  {
   78: 	     scratch[0]='1';
   79: 	     *exp += 1;
   80: 	  }
   81:      }
   82:    
   83:    scratch[i]='\0';
   84:    
   85:    return scratch;
   86: }
   87: 
   88: #ifdef TEST
   89: int main(int argc, char ** argv)
   90: {
   91:    int a, b;
   92:    char * conv=ecvt(9e0,20,&a,&b);
   93:    
   94:    printf("ecvt Test: %f -> %s, %d, %d\n",9e0,conv,a,b);
   95: }
   96: #endif

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